If Neal actually IS Peter Pan though, I think a lot of his behavior could be explained by that. The jealousy and bad decisions are marks of immaturity. I think he feels bad for what happened and still loves Emma, but at the same time I don’t think he has the emotional maturity to open up and reverts to being semi-flirtatious and sarcastic to cover it. When he can’t cover his emotions, you can see the difference. One of the moments I’m thinking of is when Rumple is trying to apologize as he’s dying and Neal responds “But I’m still angry.” His voice there just sounds so childlike and “small” but the situation won’t let him revert to his normal sarcasm. Neal is going to have to do a lot of emotional “growing up”.